<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
</html>
<script>
<!--    转大写-->
    console.log("abc".toUpperCase());

// let data = targetValue || defalutValue; 优雅地为变量赋值默认值
let name = "" || "lzm";

console.log(name);

</script>